The invention relates to a method for adjusting a television camera by means of a monitor picture, prior to scene recording, and to a device suitable therefor.
Before a television camera can generate a picture signal which is suitable for display, several adjustments must first be made at the camera, for example a black level adjustment when scene light is prevented from falling onto one or more opto-electronic pick-up devices present in the camera. The (picture) signal generated by the pick-up device in this, relative to the scene light, dark circumstances is a measure of the dark current at the pick-up device and during the adjustment the signal black level is made equal to a reference value, for example the ground potential.
A further adjustment may be performed for the peak-white value of the picture signal. For this purpose the camera is directed, with the diaphragm preset in the camera in a certain position, to a bright scene portion and the picture signal associated with this bright scene portion is fixed at a reference value, for example at 1 V.
In addition, a so-called white balance adjustment is performed for color television cameras, which implies that, starting from a fixed value for one of the color signals, for example a green color signal, the values of the other color signals, for example the red and blue color signals, are made equal for a more or less white scene portion to that of the green color signal. This adjustment may be performed by means of optical filters placed in the light originating from the scene and, furthermore, by means of electronic controls of the color signals.